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The woodland caribou Rangifer tarandus caribou in Canada’s boreal forest ecosystems are threatened. The Species At Risk Act lists R. tarandus caribou as threatened, and the Alberta Wildlife Act lists the species as threatened.

The national Species At Risk Act defines a threatened species as those which

Caribou are adapted to a boreal environment in which the main disturbance to habitat is wildfires, but human development and use of land in the boreal zone degrades the habitat and reduces the amount of habitat available to caribou (Environment Canada, Woodland Caribou, Boreal population).

Caribou are cryptic animals, and their extra-species avoidant behaviour means they do not tolerate noise, light, or the presence of other animals well.

Particular to their requirement of large, undisturbed habitat is the edge-effects the habitat can experience. If a habitat would otherwise be suitable to caribou, they may not utilize it because of small interruptions of developments. In a 6000 sq. km area, Dyer et al. found that just one percent (1%) use of the area by humans reduced the use of the same area by boreal caribou to fifty-two percent [52%; -Simon J . Dyer , Jack P . O ’ Neill , Shawn M . Wasel].

The Albertas government’s DRAFT Provincial Woodland Caribou Range Plan defines disturbed habitat as

However, the total impact on caribou habitat may be larger, as the scale of land-sat imagery used to detect and calculate habitat disturbance is large. A \(1:50000\) scale means that \(1cm\) of the satellite image corresponds to \(50000cm\), or \(0.5km\)! For most linear features like seismic lines, they do not appear on imagery such as this. The conservation efforts surrounding boreal caribou are not naive, however, and the linear features have been mapped at higher resolution scales and have been accounted for.

The general conclusion is small amounts of human usage of critical boreal caribou habitat result in significant reductions of habitat land usage.

Alberta’s boreal forests extend from the northern Rocky Mountains and northern foothills through the rest of northern Alberta.

Despite the large size of the boreal-zone in Alberta, the boreal forest ecosystems are severely degraded due to linear features (entities that occur in relatively straight lines), particularly by roads, rail-ways, and specially seismic lines.

Seismic lines are straight (or linear) clearings of trees that are used during oil and gas exploration, and historically they had an approximate width of up to ten meters (\(10m\)), but modern, lower-impact seismic lines (LIS) can have widths as small as one and a half meters (\(1.5m\)).

The extent of linear features in Alberta’s boreal forests is significant, with aprpoximately \(250000km\) of conventional seismic lines present, and sixty percent (\(60%\)) of these conventional (historical) seismic lines would require significant restoration effort, such as tree planting (Hill et al.; Government of Alberta).

Unfortunately, in the five years prior to the publication of the government of Alberta’s draft range-plan for boreal caribou conservation, all but two populations experienced decline in the percentage of undisturbed habitat available to them. The three largest decreases were in the caribou ranges of Slave Lake (\(-29.7%\)), followed by Nipsis (\(-26.5%\)), and Little Smokey (\(-20.0%\)).

Particularly worrying, is that as of the publication of Hill et al. the Little Smokey caribou range has only \(4%\) undisturbed habitat. The Little Smokey population of caribou is likely to remain designated as threatened and not self-sustaining for many decades.

The twelve populations in Alberta in the figure below are faceted (each sub-plot) by the quartile the size of their range (in hectares). The data for both the chart and table is from Hill et al.

This map from the Government of Alberta shows the ranges of boreal caribou, and other features of Alberata, and helps to visually understand the size of these ranges. The Little Smokey and Slave Lake ranges in particular are quite small for caribou, despite their large geographic size for what a human considers a large area.

The following two figures are from Dabros et al. The first is Fig. 1 of that publication, and the second is Fig 2. of that publication.

Panel \(C\) of figure 2 shows a lower-impact seismic line, and the impact on the shrubbery this method still causes. Moreover, the practice of LIS includes creating the lines in winter, which does reduce the amount of damage to the forest understory, but during winter this scare away any boreal caribou in the nearby area that hear the destruction, and they may not return for many weeks.